Introduction


This chapter will cover the history of the Hubble Telescope. The Hubble telescope was approved by congress in 1977 and production began at the Space Telescope Science Institute in Baltimore, Maryland in 1981. In 1984 the Space Telescope-European Coordinating facility began production on the telescope in Garching, Munich. On April 24th 1990 the Hubble Telescope launched.

Hubble Space Telescope

Every 96-97 minutes Hubble completes an orbit around Earth. While orbiting Hubble reflects starlight off of it's mirrors and sends photographs to other satellites which then send the photographs to Earth. Hubble is known as a Ritchey-Chretien reflector, which reflects starlight off of one mirror to a secondary mirror which then reflects the light to other satellites. Hubble's larger and primary mirror measures 2.4 meters in diameter
images-3.jpgimages-5.jpgimages-2.jpg

Discoveries Made By Hubble

The Universe was once believed to be between 10 and 20 billion years old, however Hubble has provided information which shows that the Universe is between 13 and 14 billion years old. Hubble also assisted in the discovery of Dark Matter, which is associated with the expansion of the Universe. Hubble also discovered that collapsing stars in other galaxies result in gamma-ray bursts.1107272007_1559.jpg

Servicing Missions

Hubble has undergone three servicing missions to date, with a fourth planned for 2009-2010. Servicing mission 1 took place in December 1993 and was launched to replace equipment and instruments, this process lasted 10 days. During this mission the telescope's photometer was replaced with COSTAR corrective optics. Also being replaced were several smaller cameras, 4 gyroscopes, and electrical control units, in addition, on board computers were also upgraded.

Servicing mission 2 was launched in February 1997. The most important procedure of this mission was to replace the spectrograph FOS with spectrograph STIS for improved imaging results. Also being replaced during this mission were a tape recorder, and thermal insulation for some scientific instruments, however this insulation resulted in the instruments overheating and reduced their lifespan from 4.5 years to 2 years.

Servicing mission 3A as launched in December 1999 and was launched to replace gyroscopes. Just weeks before the servicing mission a fourth gyroscope failed rendering the telescope incapable of taking photographs. This servicing mission replaced all six gyroscopes, as well as the guidance sensor and installation of a voltage and temperature improvement kit to prevent the overcharging of the battery.

Servicing mission 3B was launched March of 2002 and was launched in order to replace cameras and a new cooling system. The mission also saw the replacement of solar arrays, these solar arrays were smaller than the old arrays, resulting in a more swift movement, and also provided 30% more energy. This additional power allowed all instruments on the telescope to be run simultaneously.

Servicing mission 4 is set to be launched in 2009-2010. This mission will be the final servicing mission and will replace gyroscopes, and batteries. Repairs will also be made to spectrograph STIS. Installation of several programs will also occur. Installations include a wide-field camera, a cosmic origins spectrograph, a soft capture mechanism, and a new outer blankets layer (NOBLs). This final repairs are intended to last until at least 2014 when Hubble is set to De-orbit.
images-1.jpgimages.jpgimages-4.jpgimages-6.jpgimages-7.jpg

Conclusion

As time progresses and Hubble reaches it's end the instruments on board will begin to fail, at which point it will be unable to operate. Hubble will continue to orbit Earth until it's orbit begins to decay, as this happens astronauts will retrieve the telescope and bring it safely back to earth.

Time Line:

1977- Congress approves of Space Telescope production
1981- First productions begin in Baltimore, Maryland
1984- Production continues in Garching, Munich
1990- Hubble Space Telescope is launched into orbit
1993- First servicing mission is launched for repairs to the telescope
1997- Second servicing mission is launched for repairs to the telescope
1998- New technology is tested on Hubble for the third servicing mission
1999- The first part of the third servicing mission
2001- Continuation and finalization of the third servicing mission
2009-2010- Fourth and final servicing mission
2014?- De-Orbit of the Hubble space telescope


Sources:
http://hubble.nasa.gov/
http://www.stsci.edu/resources/
http://www.spacetelescope.org/about/index.html & http://www.spacetelescope.org/about/history/timeline.html
http://www.nasa.gov/mission_pages/hubble/main/index.html
http://hubblesite.org/the_telescope/hubble_essentials/